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Bisphenol A-glycidyl Methacrylate
Bis-GMA (bisphenol A-glycidyl methacrylate) is a resin commonly used in dental composite, dental sealants. and dental cement. It is the diester derived from methacrylic acid and the bisphenol A diglycidyl ether. Bearing two polymerizable groups, it is prone to form a crosslinked polymer that is used in dental restorations. For dental work, highly viscous bis-GMA is mixed with aluminosilicate particles, crushed quartz and other related acrylates; changes to component ratios lead to different physical properties in the end product. Bis-GMA was incorporated into composite dental resins in 1962 by Rafael Bowen. Until matrix development work in the early 2000s, bis-GMA and related methacrylate monomers were the only options for organic matrix composition. Safety Concerns have been raised about the potential for bis-GMA to break down into or be contaminated with the related compound bisphenol A. However, no negative health effects of bis-GMA use in dental resins have been found. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resin
In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on naturally occurring resins. Plants secrete resins for their protective benefits in response to injury. The resin protects the plant from insects and pathogens. Resins confound a wide range of herbivores, insects, and pathogens, while the volatile phenolic compounds may attract benefactors such as parasitoids or predators of the herbivores that attack the plant. Composition Most plant resins are composed of terpenes. Specific components are alpha-pinene, beta-pinene, delta-3 carene, and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene, and delta-cadinene. Some resins also contain a high proportion of resin acids. Rosins on the other hand are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Composite
Dental composite resins (better referred to as "resin-based composites" or simply "filled resins") are dental cements made of synthetic resins. Synthetic resins evolved as restorative materials since they were insoluble, of good tooth-like appearance, insensitive to dehydration, easy to manipulate and inexpensive. Composite resins are most commonly composed of Bis-GMA and other dimethacrylate monomers (TEGMA, UDMA, HDDMA), a filler material such as silica and in most applications, a photoinitiator. Dimethylglyoxime is also commonly added to achieve certain physical properties such as flow-ability. Further tailoring of physical properties is achieved by formulating unique concentrations of each constituent. Many studies have compared the lesser longevity of resin-based composite restorations to the longevity of silver- mercury amalgam restorations. Depending on the skill of the dentist, patient characteristics and the type and location of damage, composite restorations can have s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Sealant
Dental sealants (also termed pit and fissure sealants, or simply fissure sealants) are a dental treatment intended to prevent tooth decay. Teeth have recesses on their biting surfaces; the back teeth have fissures (grooves) and some front teeth have cingulum pits. It is these pits and fissures that are most vulnerable to tooth decay because food and bacteria stick in them and because they are hard-to-clean areas. Dental sealants are materials placed in these pits and fissures to fill them in, creating a smooth surface which is easy to clean. Dental sealants are mainly used in children who are at higher risk of tooth decay, and are usually placed as soon as the adult molar teeth come through. Background Dental caries is an upset of the balance between loss and gain of minerals from a tooth surface. The loss of minerals from the teeth occurs from the bacteria within the mouth, fermenting foods and producing acids, whereas the tooth gains minerals from our saliva and fluoride that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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